Ultra-hard materials are often used in cutting tools and rock drilling tools. Polycrystalline diamond material is one such ultra-hard material, and is known for its good wear resistance and hardness. To form polycrystalline diamond, diamond particles are sintered at high pressure and high temperature (HPHT sintering), as for example at pressure equal to or greater than 50 kbar and temperature equal or great than 1350° C., to produce an ultra-hard polycrystalline structure. A catalyst material is added to the diamond particle mixture prior to HPHT sintering and/or infiltrates the diamond particle mixture during HPHT sintering in order to promote the intergrowth of the diamond crystals during HPHT sintering, to form the polycrystalline diamond (PCD) structure. Metals conventionally employed as the catalyst are selected from the group of solvent metal catalysts of Group VIII of the Periodic table, including cobalt, iron, and nickel, and combinations and alloys thereof. After HPHT sintering, the resulting PCD structure includes a network of interconnected diamond crystals or grains bonded to each other, with the catalyst material occupying the interstitial spaces or pores between the bonded diamond crystals. The diamond particle mixture may be HPHT sintered in the presence of a substrate, to form a PCD compact bonded to the substrate. The substrate may also act as a source of the metal catalyst that infiltrates into the diamond particle mixture during sintering.
The amount of catalyst material used to form the PCD body represents a compromise between desired properties of strength, toughness, and impact resistance versus hardness, wear resistance, and thermal stability. While a higher metal catalyst content generally increases the strength, toughness, and impact resistance of the resulting PCD body, this higher metal catalyst content also decreases the hardness and wear resistance as well as the thermal stability of the PCD body. This trade-off makes it difficult to provide a PCD having desired levels of hardness, wear resistance, thermal stability, strength, impact resistance, and toughness to meet the service demands of particular applications, such as in cutting and/or wear elements used in subterranean drilling devices.
Thermal stability can be particularly relevant during wear or cutting operations. Conventional PCD bodies may be vulnerable to thermal degradation when exposed to elevated temperatures during cutting and/or wear applications. This vulnerability results from the differential that exists between the thermal expansion characteristics of the metal catalyst disposed interstitially within the PCD body and the thermal expansion characteristics of the intercrystalline bonded diamond. This differential thermal expansion is known to start at temperatures as low as 400° C., and can induce thermal stresses that are detrimental to the intercrystalline bonding of diamond and that eventually result in the formation of cracks that can make the PCD structure vulnerable to failure. Accordingly, such behavior is not desirable.
Another form of thermal degradation known to exist with conventional PCD materials is one that is also related to the presence of the metal catalyst in the interstitial regions of the PCD body and the adherence of the metal catalyst to the diamond crystals. Specifically, the metal catalyst is known to cause an undesired catalyzed phase transformation in diamond (converting it to carbon monoxide, carbon dioxide, or graphite) with increasing temperature, thereby limiting the temperatures at which the PCD body may be used.
To improve the thermal stability of the PCD material, a carbonate catalyst has been used to form the PCD. PCD formed with a carbonate catalyst is referred to hereinafter as “carbonate PCD.” The carbonate catalyst is mixed with the diamond particles prior to sintering, and promotes the growth of diamond grains during sintering. When a carbonate catalyst is used, the diamond remains stable in polycrystalline diamond form with increasing temperature, rather than being converted to carbon dioxide, carbon monoxide, or graphite. Thus the carbonate PCD is more thermally stable than PCD formed with a metal catalyst.
However, the carbonate catalyst itself is subject to a decomposition reaction with increasing temperature, converting to a metal oxide. The carbonate may be released as CO2 gas, causing outgassing of the carbonate PCD material. This outgassing can cause volume expansion and undesirable voids, bubbles, or films on adjacent surfaces, leading to imperfections and cracks in the ultra-hard material as well as decreased wear resistance.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In some embodiments, a carbonate polycrystalline diamond body has a working surface opposite a non-working surface. The carbonate polycrystalline diamond body includes a first layer including a material microstructure including a plurality of bonded-together diamond crystals and interstitial spaces there between, a portion of the interstitial spaces being occupied by a first quantity of a magnesium carbonate, the first layer defining the working surface. At least one of the first layer or the second layer includes at least a quantity of at least one of silicon, aluminum, or a combination thereof.
In some embodiments, a method for making a carbonate polycrystalline diamond body includes combining a first quantity of diamond particles with a first quantity of magnesium carbonate to form a first layer in an enclosure, the first layer having a working surface, and placing a second quantity of magnesium carbonate in the enclosure forming a second layer. The first layer and the second layer forming an assembly. A quantity of at least one of silicon or aluminum is mixed in with or placed adjacent to at least one of the first layer or the second layer. The method further includes sintering the assembly including the at least one of silicon or aluminum at high pressure and high temperature, causing the at least one of silicon or aluminum to infiltrate at least one layer of the assembly, forming a polycrystalline diamond body.
Embodiments of the present disclosure are described with reference to the following figures.
The present disclosure relates to ultra-hard materials, and more particularly in some embodiments, to ultra-hard materials formed with a carbonate catalyst having controlled thermal decomposition, and methods for forming the same. For clarity, as used herein, the term “PCD” refers to conventional polycrystalline diamond that has been formed with the use of a metal catalyst during an HPHT sintering process, forming a microstructure of bonded diamond crystals with the catalyst material occupying the interstitial spaces or pores between the bonded diamond crystals. The term “carbonate PCD” refers to PCD formed with a carbonate catalyst, forming a microstructure of bonded diamond crystals with the carbonate catalyst material occupying the interstitial spaces or pores between the bonded diamond crystals.
A region of a carbonate PCD material 10 is schematically illustrated in
In some embodiments, a carbonate PCD body is formed by subjecting an ultra-hard diamond element such as a volume of diamond particles to an HPHT sintering process in the presence of a carbonate catalyst such as magnesium carbonate (MgCO3). In an embodiment, the carbonate PCD body is formed by mixing diamond particles 14 with the carbonate catalyst 16 before HPHT sintering to create the carbonate PCD body. The formed carbonate PCD body is subsequently heat-treated under vacuum or at atmospheric pressure at a temperature of approximately 1100° C. to 1200° C. to convert a portion of the carbonate catalyst into an oxide, while releasing a gas. Heat treatment may occur in a furnace, such as vacuum furnace. In embodiments including a MgCO3 carbonate catalyst, the oxide is magnesium oxide (MgO), while the gas is carbon dioxide (CO2). In some embodiments including an MgCO3 carbonate catalyst, the MgCO3 carbonate catalyst contains a SiO2 impurity in the range of 1.5 wt % to 1.8 wt %. In some embodiments, the MgCO3 carbonate catalyst contains 1.5 wt % SiO2.
With reference to
Generally, when a non-metal catalyst such as a carbonate is used in forming a carbonate PCD body, the diamond remains stable while being converted to polycrystalline diamond form during HPHT sintering with increasing temperatures up to 1200° C., without being converted to carbon dioxide, carbon monoxide, or graphite. However, during subsequent heat-treatment cycles of the formed carbonate PCD under atmospheric pressure or vacuum (after HPHT sintering) for the purpose of decomposing the carbonate catalyst, the PCD may develop cracks at temperatures between 800° C. and 1200° C., and may be subject to graphitization. This threshold temperature of 1200° C. is very close to the thermally stable temperature of PCD under vacuum. In some embodiments, by controlling the thermal decomposition of the carbonate catalyst, a crack-free working surface 23 of the carbonate PCD body is formed. Thus, in order to prevent or reduce thermal degradation of the PCD after HPHT sintering and during heat-treatment cycles below the threshold 1200° C. (ranging from temperatures between 1100° C.-1200° C.), various embodiments provide for a MgCO3 carbonate catalyst that infiltrates the diamond particles during HPHT sintering and fully (or mostly) decomposes at a temperature below the 1200° C. threshold during subsequent heat-treatment cycles.
Generally, a carbonate catalyst such as MgCO3 may begin to decompose at a temperature of approximately 400° C. at ambient pressure. The thermal decomposition temperature of MgCO3 is related to the pressure. For example, MgCO3 will remain in its major phase without fully decomposing when heat-treated after HPHT sintering for one hour under vacuum to a temperature of 1200° C., as for example shown in
However, by mixing the components of the first, second, and/or third layer with a Si and/or Al compound before sintering, according to various embodiments disclosed herein, full (or nearly full) thermal decomposition of the MgCO3 carbon catalyst during a post-HPHT sintering heat-treatment temperature below 1200° C. may be realized. When the Si and/or Al compound mixed into the first, second, and/or third layer, according to embodiments of the present disclosure, reacts with the MgCO3 catalyst, MgSiO3, Mg2SiO4, MgAl2O4 and/or combinations thereof is formed. The compounds formed as a result of the reaction of the Si and/or Al compounds with the MgCO3 promote thermal decomposition of the MgCO3 at a lower temperature than the temperature of thermal decomposition under vacuum during heat-treatment cycles when Si and/or Al is/are not included. According to various embodiments, the MgCO3 will enter the full thermal decomposition phase at or below the 1200° C. threshold for thermal degradation of the carbonate PCD, itself, and thus cause a reduction in the cracks often formed in the carbonate PCD at heat treatment cycles of temperatures between 800° C. and 1200° C. As shown in
In some embodiments, by increasing the percentage by weight of MgCO3 premixed with the diamond particles of the second layer, or as part of an additional third layer, thermal decomposition of the MgCO3 at a lower temperature is promoted, causing thermal decomposition under vacuum during heat-treatment cycles. The additional percentage by weight of MgCO3 results in the formation of larger pore channels in the carbonate PCD during HPHT sintering, allowing the CO2 gas formed during subsequent thermal decomposition of the MgCO3 to more easily release from the PCD body. As shown in Table 3 below, in one embodiment, the phase ratio of MgO to MgCO3, after heat-treating a carbonate PCD body under vacuum at a temperature of 1100° C. (after HPHT sintering), increases as the percentage by weight of MgCO3 premixed with the diamond particles or as part of a third layer is increased. In one embodiment including a 3% premixed percentage by weight of MgCO3, the phase ratio is approximately 0.07, while in another embodiment including a 5% premixed percentage by weight of MgCO3, the ratio increases to 1.63, and in another embodiment including a 7% premixed percentage by weight of MgCO3, the ratio increases to 13.85.
However, an increase in the percentage by weight of MgCO3 premixed into a layer, while promoting thermal decomposition of the catalyst at a lower temperature, can also decrease the wear resistance of the PCD body surface as a result of the formation of larger pore channels on the surface carbonate PCD body and as a result of the decrease in diamond density. In various embodiments, the increased percentage by weight of MgCO3 is added to the second layer, and/or as part of the additional third layer, while the first layer, which will form a working surface of the carbonate PCD, optionally includes a comparably decreased percentage by weight of MgCO3. As a result of the increased percentage by weight of MgCO3 premixed into the second and/or third layers, these layers may be generally thicker than the first layer, which contains a lesser quantity of the MgCO3 premixed into the layer. In these embodiments, the higher concentration of the MgCO3 catalyst premixed into the second and/or third layers may promote thermal degradation of the MgCO3 catalyst at a lower temperature than the temperature at which thermal degradation of the MgCO3 of the first layer will occur because of the formation of larger pore channels in the second and/or third layers due to the higher concentration of the MgCO3 catalyst, making it easier for CO2 gas to be released from these layers. Accordingly, in some embodiments, the MgCO3 catalyst in the second and/or third layers, which will be heat-treated after HPHT sintering, may be more fully decomposed at a lower temperature than the MgCO3 catalyst in the first layer. The result of this variance in thermal decomposition properties of the layers after HPHT sintering and initial heat-treatment cycles due to the difference in the MgCO3 catalyst concentrations in the layers is that the carbonate PCD may form minimal to no cracks at the working surface side of the first layer during subsequent heat-treatment cycles because the CO2 decomposed from the first layer can be quickly released through the thinner first layer, rather than remain trapped inside the thicker second and/or third layers. However, because the Si and/or Al compounds may promote thermal decomposition of the MgCO3 catalyst at a lower temperature are not catalysts, in order to decrease wear resistance at the working surface, the amount of these compounds that accumulates at the working surface after mixing these Si and/or Al compounds into the first, second, and/or third layer, in some embodiments, may be minimized or reduced. In some embodiments, infiltrating the first layer at the working surface side with additional MgCO3 catalyst that has not been premixed with diamond particles, for example by placing the third layer or another fourth layer of MgCO3 catalyst adjacent to the first layer so that the first layer is sandwiched between the third or fourth layer and the second layer, allows for the formation of a working surface with minimal cracks, and maintained wear resistance. In some embodiments, after HPHT sintering and subsequent heat-treatment cycles, the additional MgCO3 catalyst in the third or fourth layer, adjacent to the first layer, may fully decompose, allowing the Si and/or Al compound to infiltrate through the remaining layers, and resulting in the formation of a working surface having reduced to no cracks.
A method for forming the carbonate PCD body with a distribution of Si and/or Al elements is shown in
In some embodiments, the method includes introducing a third layer 26 including a Silicon (Si) and/or Aluminum (Al) compound, as well as a carbonate catalyst adjacent to the non-working surface 21 of the second layer (block 103). In various embodiments, this Si and/or Al compound includes Al, Si, SiO2, Al2O3, SiC, Al3C, and/or combinations thereof. In some embodiments, the Si and/or Al compound is included at about 1.5 wt % (with respect to the weight of the carbonate catalyst). In other embodiments, the Si and/or Al compound is SiC included at 0.5 wt % (with respect to the weight of the layer). In other embodiments, instead of using a third layer, the Si and/or Al compound can be combined directly with the second layer 24 forming a mixture of diamond particles, mixed with the second percentage of carbonate catalyst, and mixed with the Si and/or Al compound for forming the second layer 24. In other embodiments, the Si and/or Al compound is introduced to the separate third layer 26, the Si and/or Al compound is applied as separate layer 29 adjacent to the second layer 24, and disposed at an opposite surface from the first layer working surface 23, and adjacent to the non-working surface 21, as, for example, shown in
In other embodiments, as shown in
With reference again to
By way of example,
In some embodiments, where the Si and/or Al compound is directly mixed with the particles and catalyst of the second layer or in the separate third layer adjacent to the second layer prior to HPHT sintering, the resulting carbonate PCD after HPHT sintering has a first layer or working surface with a higher concentration of the Si and/or Al compound. And, as a result of the first layer including the working surface having a percentage of the carbonate catalyst less than that of the second layer prior to HPHT sintering, a greater percentage of the carbonate catalyst may be thermally decomposed at the first layer working surface, than at the second layer or non-working surface, during heat-treatment cycles. The higher concentration of the Si and/or Al compound formed at the first layer including the working surface results in a lower thermal decomposition temperature for the carbonate catalyst than there would be otherwise without the Si and/or Al compound at the working surface and throughout the remainder of the carbonate PCD, including throughout the second layer. In other embodiments, the decomposition temperature of the first layer may be lower than, equal to, or even greater than the decomposition temperature of the second layer, as a result of the Si and/or Al compound introduced prior to HPHT sintering. However, the resulting thermal decomposition temperature of the first layer will be less than the thermal decomposition temperature for a carbonate catalyst not including a Si and/or Al compound. The result is a diamond compact including a carbonate PCD body with a distribution of Si and/or Al elements.
A diamond compact 30 according to an embodiment is shown in
The diamond compact 30 shown in
In other embodiments, rather than the carbonate catalyst, and/or the Si and/or Al compounds being mixed in or pre-mixed with the diamond particles of the first layer, and/or the second layer, the carbonate catalyst and/or the Si and/or Al compounds may be applied as separate layer(s) adjacent to the first layer or the second layer, or the third layer, or any other layer including or not including diamond particles. The separate layer(s) including the carbonate catalyst and/or the Si and/or Al compounds may then infiltrate into the corresponding adjacent layer during HPHT sintering.
Although only a few embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from embodiments disclosed herein. Accordingly, all such modifications are intended to be included within the scope of this disclosure. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.
This application is a divisional of U.S. patent application Ser. No. 14/209,768 filed on Mar. 13, 2014, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/801,182 filed on Mar. 15, 2013, and U.S. Provisional Patent Application Ser. No. 61/843,655 filed on Jul. 8, 2013, the entire contents of each are fully incorporated herein by reference.
Number | Date | Country | |
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61801182 | Mar 2013 | US | |
61843655 | Jul 2013 | US |
Number | Date | Country | |
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Parent | 14209768 | Mar 2014 | US |
Child | 15382770 | US |